Separate parts in a staff

Is there a way to cut one voice out of a staff to move it to a separate staff?
What I did was compose in a piano score - melody line in the treble clef, bass line in the bass clef, and piano background chords in both clefs, using different voices. Now that I have that sounding OK, I'd like to move the melody to a horn and the bass line to a separate bass instrument. In other words, move one voice, as a group, from the piano to a different instrument?